Infrared upconversion detection based on two-dimensional material/silicon tunable metasurface heterostructures for telecommunication

We introduce a heterostructure integrating a two-dimensional nonlinear GaSe film on a silicon metasurface supporting quasi-bound states in the continuum (BIC) mode, to enhance the nonlinear sum-frequency generation (SFG) process in the GaSe film, where incoming shortwave infrared (SWIR) photons are upconverted to visible photons. The wavelength selectivity in the silicon metasurface corresponding to different configurations enables the GaSe film/silicon tunable metasurface heterostructure to have a response in the range of 1500–1630 nm, covering the telecommunication C and L bands. The response spectrum is derived from the dual quasi-bound states in the continuum resonance of the metasurface structure, and the pump light and signal light correspond to the dual quasi-bound states in the continuum resonances of the metasurface structure. The high quality-factor of the quasi-bound states in the continuum resonance brought by the metasurface greatly improves the density of the electromagnetic field near the GaSe film, thus improving the sum-frequency generation conversion efficiency in the GaSe film. The pump and signal corresponding to the dual quasi-bound states in the continuum resonances introduced by the silicon metasurface are designed in the telecommunication band, while the sum-frequency light is located in the range that can be directly detected by a silicon detector. The low noise level in a silicon detector can guarantee the high sensitivity detection of shortwave infrared light. The results indicate that the upconversion detector attained a peak detectivity of 1.4 × 1012 Jones at 1555.1 nm, comparable to commercial broadband InGaAs detectors (Thorlabs).